Orthogonal variable spreading code (OVSF) allocation telecommunications network

A code allocation unit (100) of a radio access telecommunications network allocates one of plural Orthogonal Variable Spreading Factor (OVSF) codes to a radio access connection for use as a channelization code. The plural Orthogonal Variable Spreading Factor (OVSF) codes are defined by a binary code tree structure having a root and plural code levels, each node of the tree corresponding to one code and having a spreading factor defined by its level (k) in the tree structure. When a code of level k=i is requested for the connection, the code allocation unit selects, to be an allocated OVSF code, a free code of the ith level whose subtree structure from the root of the code tree has a largest combined weight. According to the inventive technique, the code allocation unit allocates OVSF codes in a manner to enable users to operate at high data rate transmission/reception. As one aspect, allocation is performed by assigning new users to the part of the tree that contains the most number of users, thereby keeping the number of users low in other parts of the tree, and thus increasing the probability that codes of these parts of the code tree will be free for high data-rate codes. When all codes are equally weighted, the technique allocates a code based on the number of users in different subtrees, and selects the code whose subtree structure (from the root of the code tree) has the most number of users. The technique is based upon the assumption that the probability of a short term release of a presently unavailable higher level code will increase if the number of users in the codes subtree is minimized.